What is network renderer?
Blender's network renderer allows you to link to other PCs -- Apple, Windows, Linux -- and distribute your render job to many computers... speeding up the job overall... It is a job management tool to make rendering many frames faster, by spreading the work across multiple platforms.

Here's a good video on using network render and in setting up a render farm  in your office:
https://cgcookie.com/archive/setting-up-a-render-farm/